Appliance configured to circulate air during a wash cycle

ABSTRACT

An appliance such as a dishwasher is configured to re-circulate air to reduce the amount of air with high moisture content that is expelled from the dishwasher. In one embodiment, the dishwasher comprises a wash zone in which objects are positioned to be washed and a door assembly, secured to the dishwasher in sealing engagement. Air from an upper region of the wash zone is drawn into a door cavity in the door assembly and re-circulated to a lower region of the wash zone. Inside of the door cavity is a thermal sink with a surface on which vapor in the air condenses, thereby lowering the relative humidity of the air that is ejected from the door assembly and into the lower region of the wash zone.

BACKGROUND OF THE INVENTION

1. Technical Field of the Disclosure

The subject matter of the present disclosure relates generally to appliances, and more particularly, to embodiments of a dishwasher with a wash zone and a door assembly which passes a fluid (e.g., air) from an upper portion to a lower portion of the wash zone.

2. Description of Related Art

Appliances such as household dishwashers operate by way of several fill and drain cycles. During each of these cycles, washing fluid such as water flows into a wash tub, which is already sufficiently hot, or may be heated in the wash tub using a heating element, and circulates in a manner that cleans the objects (e.g., dishes, dishware, etc.) disposed. therein. After the expiration of a period of circulation, the appliance drains the washing fluid from the appliance and flows in fresh washing fluid, which it then circulates to continue cleaning of the objects.

Many dishwashers also initiate a drying cycle to remove excess water from the objects. The drying cycle may utilize the heating element noted above, which raises the temperature of the air inside of the wash tub. Preferred temperatures cause evaporation of the washing fluid from the objects. However, because the evaporated washing fluid mixes with the air as vapor, use of the drying cycle raises the relative humidity inside of the dishwasher and saturates the air. Thus, to continue drying, most dishwashers must expel the moist, vapor-laden air to the environment outside of the dishwasher through vents and other openings.

The high moisture content of such expelled air can affect surrounding items such as cabinetry, counter tops, as well as surfaces covered with paint and wall paper.

There is a need, therefore, to improve the performance of appliances such as dishwashers, and more particularly, there is a need for dishwashers that reduce the amount of air expelled during the drying cycle.

BRIEF SUMMARY OF THE INVENTION

Broadly stated, dishwashers of the present disclosure exhibit improved performance with respect to drying of objects disposed therein. These dishwashers re-circulate air inside of the dishwasher rather than expel warm moist air. This feature eliminates the need to provide vents or other outlets to expel the warm moist air. Moreover, these dishwashers do not inject latent heat (such as by way of additional heating devices) or require additional components (e.g., ducting) that alter the footprint of the dishwasher. Rather the dishwashers below utilize the existing framework of the appliance, thereby delivering the enhancements with limited impact on the construction and appearance of the product.

In one embodiment, a door assembly comprises a peripheral wall forming a door cavity, the peripheral wall having a first opening and a second opening exposing the door cavity to the environment. The door assembly also comprises a thermal sink disposed in the door cavity and an air moving device that is configured to draw air through the first opening and into the door cavity. In one example, the thermal sink is configured with a surface on which condenses vapor in the air.

In another embodiment, an appliance comprises a wash zone in which objects can be positioned to be washed. The appliance also comprises a door assembly configured to seal the wash zone, the door assembly having a peripheral wall surrounding a door cavity in which is disposed a thermal sink with a surface on which condenses vapor in the air. In one example, the door assembly is configured to draw air into the door cavity from an upper region of the wash zone and to expel the air from the door cavity into a lower region of the wash zone.

In yet another embodiment, a method of operating a dishwasher, in which the method comprises a step for activating an air moving device located proximate the upper region, wherein the air moving device is configured to generate an outward flow of air from the wash zone into the door cavity. The method also comprises a step for regulating a heating element from a first power level to a second power level in response to a change in a characteristic of the environment of the dishwasher, wherein the air passes through the door cavity in thermal relation to a thermal sink.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is now made briefly to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of an exemplary embodiment of an appliance;

FIG. 2 is a side, cross-section view of another exemplary embodiment of an appliance;

FIG. 3 is a cross-section view of a thermal sink for use in an appliance such as the appliances of FIGS. 1 and 2;

FIG. 4 is a cross-section view of a duct for use in an appliance such as the appliances of FIGS. 1 and 2;

FIG. 5 is a side, partial broken view of another exemplary embodiment of an appliance;

FIG. 6 is a schematic diagram of an example of a control configuration for use with an appliance such as the appliances of FIGS. 1, 2, and 5; and

FIG. 7 is a flow diagram of an example of a method of operation of an appliance such as the appliances of FIGS. 1, 2, and 5.

Where applicable like reference characters designate identical or corresponding components and units throughout the several views, which are not to scale unless otherwise indicated.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 depicts in schematic form an exemplary embodiment of an appliance 100 that deploys a drying system to re-circulate air within the appliance. The appliance 100 embodies a dishwasher 102, which is typically a household dishwasher that can be installed in kitchens, pantries, and related areas in a home. It is contemplated, however, that other types and configurations of dishwashers, including commercial dishwashers and dishdrawers may realize the benefits of the drying system disclosed herein. The identification of a household dishwasher therefore does not limit the appliance 100 to any particular configuration of the dishwasher 102.

The dishwasher 102 includes a cabinet 104 that encloses a wash zone 106 in which objects can be positioned to be washed. The cabinet 104 also encloses a sump zone 108, which is below the wash zone 106 and captures a washing fluid 110 therein. A door assembly 112 seals the wash zone 106 to prevent or retard liquid from exiting the dishwasher 102. The door assembly 112 has a door cavity 114 which defines a generally open, hollow area. This area houses a variety of components and elements including a thermal sink 116 with a surface 118 on which water vapor condenses as generally indicated by condensed fluid 120.

The condensed fluid 120 originates as vapor in air re-circulated about the dishwasher 102 as mentioned above and depicted in FIG. 1 as airflow pattern 122. Airflow pattern 122 includes an outward flow 124 and an inward flow 126, each of which identifies a direction of airflow, respectively, into the door cavity 114 from the wash zone 106 and from the door cavity 114 into the wash zone 106. The airflow pattern 122 also includes a condensing flow 128, which promotes formation of the condensed fluid 120 as discussed in more detail below. The condensed fluid 120 flows into the sump zone 108 as indicated by condensed fluid flow 130.

Characteristics of the outward flow 124 and the inward flow 126 define operation of the drying system proposed herein. These characteristics include the temperature (T) and relative humidity (RH) of the air that circulates about the dishwasher 102. In context of the present example, the outward flow 124 has an outward temperature (T_(outward)) and an outward humidity (RH_(outward)) and the inward flow 126 has an inward temperature (T_(inward)) and an inward humidity (RH_(inward)). As discussed more below, operation of the dishwasher 102 changes these characteristics and in one embodiment these characteristics change as identified in Table 1 below.

TABLE 1 Flow Characteristics T_(outward) > T_(inward) RH_(outward) > RH_(inward)

The thermal sink 116 facilities changes in the relative humidity (RH) such as when the thermal sink 116 exchanges heat with the air in the condensing flow 128. In one embodiment, the thermal sink 116 is at a temperature T_(sink) that is less than the outward temperature T_(outward). The resulting temperature difference promotes transfer of heat front the warmer air of the condensing flow 128 to the cooler surface 118 of the thermal sink 116. Heat transfer precipitates condensation of moisture in the condensing flow 128 onto the surface 118, thereby forming the condensed fluid 120. Formation of the condensed fluid 120 also reduces the amount of water vapor in the condensing flow 128 as reflected by the change in the relative humidity (RH) (e.g., RH_(outward) is greater than RH_(inward)). In some configurations, the condensed fluid 120 flows off of the thermal sink 116 to the sump zone 108 as the condensed fluid flow 130.

The temperature of the thermal sink 116 can be passively controlled. That is, the thermal sink 116 dissipates heat exchanged with the condensing flow 128 without aid from external devices, e.g., a fan. However, this does not foreclose the use of external devices and in some examples it may be desirable to place the thermal sink 116 in heat transfer relation with a heat exchanger. Artisans skilled in the appliance arts will generally recognize properly configured heat exchangers (and related devices), therefore details are not necessary.

FIG. 2 illustrates another exemplary embodiment of an appliance 200. Like numerals are used to identify like components as between FIGS. 1 and 2, but the numerals are increased by 100. For example, the appliance 200 comprises a wash zone 206 and a sump zone 208 with a washing fluid 210. The appliance also has a door assembly 212, a door cavity 214, and a thermal sink 216 located therein. Also depicted is an airflow pattern 222 with an outward flow 224, an inward flow 226, and condensing flow 228. Likewise there is also shown a condensed fluid flow 230, which flows into the sump zone 208.

In the present example, the door assembly 212 comprises a peripheral wall 232 that surrounds the door cavity 214. The peripheral wall 232 comprises an inside wall 234, an outside wall 236, a top wall 238, and a bottom wall 240. Openings 242 include a first opening 211 (also “an upper opening 214”) and a second opening 216 (also “a lower opening 246”) that facilitate flow connection of the door cavity 214 and, respectively, an upper region 248 and a lower region 250 of the wash zone 206.

Proximate the first opening 244 is an air moving device 252 such as a fan element 254 that is configured to intake air from the wash zone 206 and form the outward flow 224. In one embodiment, a duct 256 is coupled at a first end 258 to the fan element 254 and extends in a generally downward direction towards the bottom of the door cavity 214. The duct 256 terminates at a second end 260, which is coupled to the second opening 246. The second opening 246 is configured for air to be expelled as the inward flow 226 into the wash zone 206.

The duct 256 also has a heat exchange area, generally identified by 262. The heat exchange area 262 exposes the air moving inside of the duct 256 to the thermal sink 216. Moreover, while in one example fluid that condenses on the thermal sink 216 can flow into the sump zone via the duct 256, in another example, a conduit 264 is coupled to the duct 256 and to the sump zone 208. The conduit 264 provides another path that permits condensed fluid flow 230 to flow into the sump zone 208.

The duct 256 forms a pathway through the door assembly 212. This pathway channels and/or directs most, if not all, of the air that flows between the wash zone 206 and the door cavity 214. This configuration reduces the likelihood that moist air will enter into the door cavity 214 and escape as water vapor to the environment surrounding the appliance 100. In one embodiment, in lieu of the duct 256, the door cavity 214 acts as the pathway, wherein the structure of the door cavity 214 is sufficient to direct and/or channel the air to and from the wash zone 206 via the thermal sink 216.

Ducts for use as the duct 256 are constructed of conduit and tubing (e.g., a tube) that have a generally hollow interior through which air can move. Metals, plastics, and composites are suitable materials for use in this capacity, with selection in one example relying on the size and configuration of the door assembly 212 and/or the door cavity 214. It is contemplated, for example, that the door cavity 214 may house other elements such as electronics, the position of which may prevent implementation of the duct 256 as a generally straight, elongated member (as illustrated). Accommodation of these elements might require that the duct 256 is deployed in shapes with bends and turns so as to couple the first opening 244 and the second opening 246. Embodiments of the appliance 200 are also contemplated, however, wherein the duct 256 is formed with elements that are secured within the confines of door cavity 214. That is, the duct 256 and/or recirculation pathway can be embodied using materials (e.g., sheets of metal or plastic) that are arranged and secured within the door cavity 214 to channel the air, e.g., from the first opening 244 to the second opening 246 via the thermal sink 216.

The thermal sink 216 can comprise a variety of materials and can be manufactured using myriad processes and techniques. The thermal sink 216 may comprise a single unitary structure that is formed monolithically with a form factor such as a plate, block, cylinder, and/or sphere. Other configurations of the thermal sink 216 are formed with separate pieces, layers, laminations, etc., that are assembled together with fasteners such as adhesives.

The thermal sink 216 is amenable to materials such as metals, plastics, and composites, and more particularly to those materials that are related to consumer goods and devices. Therefore selection is often dictated by factors such as cost, size, shape, weight, and reliability. Materials include aluminum, steel, stainless steel, as well as combinations and derivations of these and other materials with effective thermal-conductive properties. To promote heat transfer and condensation, in one example the thermal conductivity of the material is at least about 15 W/m*K.

Still other examples of the thermal sink 216 (and the duct 256) comprise phase change materials (PCMs) or latent heat storage units (LHUs), which melt and solidify at certain temperatures and which store and release large amounts of energy. Varieties of PCMs, which include salt hydrates, paraffins (e.g., paraffin wax), and fatty acids, are typically solid at room temperature (e.g., about 22° C.) and liquefy as temperatures increase. However, PCMs that are also compatible exhibit a wide range of transition temperatures such as from about 0° C. to about 100° C. During liquefaction heat is absorbed and stored. Conversely, the stored heat is released during solidification, which can occur when heat is transferred to the environment and no heat is received such as from and/or during operation of the appliance 200.

In one embodiment, when implemented in the thermal sink 216, PCMs are located proximate the surface 218 and in a position to absorb and store heat energy from the condensing flow 228. Liquefaction will likely occur, for example, when the outward flow 224 is at an elevated temperature such as is consistent with operation of the appliance 200 during the drying portion of a wash cycle. Changes in the temperature of the outward flow 224 that correspond to the completion of the drying portion (and/or the wash cycle) will thereafter promote solidification, thereby releasing the heat stored by the PCM and preparing the PCM for the next wash cycle.

Use of phase change materials and construction of certain elements of appliances described herein are discussed next in connection with FIGS. 3 and 4, In FIG. 3, a thermal sink 300 comprises a thermal body 302 with a surface 304 (e.g., the surface 118, 218) on which fluid is condensed. The thermal body 302 comprises a first material 306 that forms in one example the surface 304. Internal to the first material 306 is a second material 308, and more particularly, the second material 308 comprises a phase change material (PCM), generally identified by spheres 310, which are suspended in a matrix material 312.

A duct 400 is illustrated in FIG. 4. The duct 400 comprises a first member 402 (also “an inner member 402”) and a second member 404 (also “an outer member 404”) that surrounds the first member 402. The second member 404 comprises an inner boundary 406, an outer boundary 408, and a phase change material (PCM) disposed therebetween. In the present example, the phase change material (PCM) is in the form of spheres 410 that are suspended in a matrix material 412. The first member 402 forms a hollow interior 414 through which fluid such as air can flow.

The inventors note that use of spheres (e.g., the spheres 310, 410) and the matrix material (e.g., the matrix material 312, 412) is but one representation of PCMs. Other embodiments may arrange constituent components of the PCMs and derivatives may in different combinations of materials and material structure. Spheres are often used, for example, to represent the incorporation of paraffin wax material, which liquefies and solidifies as discussed above.

Other structural element are also contemplated but not necessarily illustrated in the examples of the thermal sink 300 and the duct 400. In one embodiment, structures such as boundaries, casings, containers, and related constructions retain the PCMs. These structures prevent the PCMs, upon liquefaction to the fluid-like phase, from flowing away from the surface at which condensation is to occur.

Turning next to FIG. 5, another exemplary embodiment of an appliance 500 is described below in which there is depicted a side elevation view of a dishwasher 502 partially broken away. The recirculation pathway discussed previously and comprising one or more of the thermal sinks (e.g., the thermal sinks 116, 216, and 300), the ducts (e.g., the ducts 256 and 400), and the air moving device (e.g., the air moving device 252) described above and contemplated herein may be practiced in the dishwasher 502, as well as other configurations and types of appliances other than just the dishwasher 502 (and the appliance 100 and 200 above). Although not shown in the details of FIG. 5, the recirculation pathway is implemented using similar components, features, implements, and concepts as discussed with reference to FIGS. 1-4 above. Therefore details of these components are not provided in the discussion below, unless necessary to clarify particular subject matter described in connection with FIG. 6 and/or embodiments of the dishwasher 502.

By way of example, the dishwasher 502 includes a cabinet 504 having a tub 506 therein and forming a wash chamber 508. The tub 506 includes a front opening (not shown in FIG. 6) and a door assembly 510 (e.g., door assembly 112, 212) with a hinged bottom 512 such as for movement between a normally closed vertical position (shown in FIG. 6) wherein the wash chamber 508 is sealed shut for washing operation, and a horizontal open position (not shown) for loading and unloading of dishwasher contents.

Guide rails 514 including an upper guide rail 516 and a lower guide rail 518 are mounted on tub side walls 520. The guide rails 514 accommodate one or more racks 522 such as an upper rack 524 and a lower rack 526 (hereinafter, “the racks”), respectively. The racks can be fabricated from known materials into lattice structures including a plurality of elongated members 528, and each is adapted for movement between an extended loading position (not shown) in which at least a portion of the racks are positioned outside the wash chamber 508, and a retracted position (shown in FIG. 5) in which the rack is located inside the wash chamber 508. In one implementation, a silverware basket (not shown) is removably attached to lower rack 526 for placement of silverware, utensils, and the like that are too small to be accommodated by either one or both of the racks contemplated herein.

A control input selector 530 such as a keypad is mounted at a convenient location on an outer face 532 of door assembly 510 and is coupled to known control circuitry. The control input selector 530 is also coupled to other control mechanisms (not shown) for circulating fluids such as water and dishwasher fluid in the tub 506. In one embodiment, the dishwasher 502 includes a machinery compartment 534 located below a bottom sump portion 536 (e.g., sump zone 508) of the tub 506, and a heating element 538 is disposed proximate the bottom sump portion 536.

In one embodiment, the dishwasher 502 includes a lower spray-arm assembly 540, which is mounted for rotation within a lower region 542 of the wash chamber 508 and above bottom sump portion 536 so as to rotate in relatively close proximity to the lower rack 526. A mid-level spray-arm assembly 544 is located in an upper region 546 of the wash chamber 508 in close proximity to the upper rack 524. The mid-level spray-arm assembly 544 is located at a height above the lower rack 526 sufficient to accommodate items such as a dish or platter (not shown) that is placed in lower rack 526. In a further embodiment, an upper spray-arm assembly (not shown) is located above the upper rack 524, again being located at a height sufficient to accommodate items expected to be placed in the upper rack 524, such as a glass (not shown) of a selected height.

One or more of the spray arm assemblies (e.g., the lower spray-arm assembly 540, the mid-level spray-arm assembly 544, and the upper spray-arm assembly) includes discharge ports 548 such as one or more spray jets 550, which are effectively orifices for directing the washing fluid onto objects (e.g., dishes and dishware) located in the racks. The angle of the spray jets 550 can vary, depending in part on the size of the wash chamber 508, the location of the spray arm assembly, and the number of racks, among many factors.

The arrangement of the spray jets 550 in the spray arm assemblies can result in a rotational force as the washing fluid flows through the spray jets 550. The resultant rotation of spray arm assemblies provides coverage of dishes and other dishwasher contents with the washing fluid. In one embodiment, one or more of the spray arm assemblies is likewise configured to rotate, generating in one example a swirling spray pattern above and below, e.g., the upper rack 524.

A variety of hardware platforms can be used to implement the concepts of the present disclosure. The example of FIG. 6 provides a schematic diagram an exemplary hardware platform 600 for use in, e.g., the appliance 100, 200, and 500, and related embodiments (“the appliances”). The hardware platform 600 includes a controller 602, which includes a processor 604, a memory 606, and control circuitry 608 configured for general operation of the appliances. The control circuitry 608 comprises a timing circuit 610, a pump control circuit 612, and a fan control circuit 614, a heater control circuit 616, and an environment control circuit 618. All of these components are coupled together and communicate to one another when applicable via one or more busses 620.

The hardware platform 600 further includes a fan 622 and a pump 624, as well as a sensor 626 such as a temperature and/or humidity sensor and a heater device 628, which is useful to regulate and implement a drying cycle in the appliance. In one embodiment, the controller 602 is coupled to a control panel 630 that includes one or more wash cycle controls 632 and an indicator control 634. When implemented in the appliances, the controller 602 effectuates operation of various elements of the appliance such as in response to inputs from the control panel 630. The timing circuit 610, of which various configurations are contemplated, is provided to indicate times and time periods to, e.g., change the configuration of the appliance as between the one or more of the wash cycles. These time periods may be selected, in connection with or wholly separate from the configuration of the appliance so as to improve the cleanliness and sanitation of the objects in the appliance as contemplated herein. The heater control circuit 616 regulates power impressed on the heater device 628 and, in one example, the heater control circuit 616 changes the power level in response to inputs from the sensor 626 or other device that monitors conditions (e.g., temperature) inside of the appliance.

The control platform 600 and its constructive components are configured to communicate amongst themselves and/or with other circuits (and/or devices), which execute high-level logic functions, algorithms, as well as firmware and software instructions. Exemplary circuits of this type include, but are not limited to, discrete elements such as resistors, transistors, diodes, switches, and capacitors, as well as microprocessors and other logic devices such as field programmable gate arrays (“FPGAs”) and application specific integrated circuits (“ASICs”). While all of the discrete elements, circuits, and devices function individually in a manner that is generally understood by those artisans that have ordinary skill in the electrical arts, it is their combination and integration into functional electrical groups and circuits that generally provide for the concepts that are disclosed and described herein.

The electrical circuits of the controller 602 are sometimes implemented in a manner that can physically manifest logical operations, which are useful to facilitate the timing of the wash cycles of the appliance including drying cycles in with the fan 622 is operated as part of the recirculation system. These electrical circuits can replicate in physical form an algorithm, a comparative analysis, and/or a decisional logic tree, each of which operates to assign an output and/or a value to the output such as to actuate the fan 622 and/or to activate the pump 624.

In one embodiment, the processor 604 is a central processing unit (CPU) such as an ASIC and/or an FPGA. The processor 604 can also include state machine circuitry or other suitable components capable of receiving inputs from, e.g. the control panel 630. The memory 606 includes volatile and non-volatile memory and can be used for storage of software (or firmware) instructions and configuration settings. Each of the timing circuit 610, the pump control circuit 612, and the fan control circuit 614, the heater control circuit 616. and the environment control circuit 618 can be embodied as stand-alone devices such as solid-state devices. These devices can be mounted to substrates such as printed-circuit boards, which can accommodate various components including the processor 604, the memory 606, and other related circuitry to facilitate operation of the controller 602 in connection with its implementation in the fluid dispensing appliances.

However, although FIG. 6 shows the processor 604, the memory 606, the timing circuit 610, the pump control circuit 612, the fan control circuit 614, the heater control circuit 616, and the environment control circuit 618 as discrete circuitry and combinations of discrete components, this need not be the case. For example, one or more of these components can be contained in a single integrated circuit (IC) or other component. As another example, the processor 604 can include internal program memory such as RAM and/or ROM. Similarly, any one or more of functions of these components can he distributed across additional components (e.g., multiple processors or other components).

The hardware platform 600 is configured to execute operational cycles on appliances (e.g., the appliances 100, 200, and 500). In one example, the processor 604 executes one or more executable instructions (e.g., software and/or firmware) that embody the various steps and phases of an operational cycle. Some of these instructions cause the processor 604 to operate the various components of the appliance such as to dispense the washing fluid into the wash zone and onto the objects positioned therein. These phases commonly include a wash phase, a rinse phase, and a drying phase. These phases may be repeated one or more times as dictated, for example, by control settings pre-set and/or pre-arranged on the appliance and useful to achieve certain levels of cleanliness of the objects to be washed.

With continued reference to FIG. 6, an example of operation of the appliance is illustrated in FIG. 7 and discussed next. In FIG. 7, there is depicted a flow diagram of a method 700 that includes several steps that can be executed by the controller 602 as contemplated herein. At a relatively high level, the method 700 comprises, at block 702, flowing air from an upper region of a wash zone into a door cavity of a door assembly, at block 704, directing the air through the door cavity and in thermal relation to a thermal sink, and at block 706, ejecting the air into a lower region of the wash zone.

Additional steps are also included in the method 700. The steps include, but are not limited to, at block 708, activating an air moving device located proximate the upper region to cause an outward flow of into the door cavity from the wash zone. The steps also include, at block 710, regulating a heating element from a first power level to a second power level in response to a change a characteristics of the environment of the wash zone.

In one embodiment, the controller 602 is operatively configured to regulate the operation of the fan 622 and/or the heater device 628 to promote evaporation of the washing fluid from the objects. In one example, the controller 602 can change the operation of the heater device 628 in response to changes in the characteristics of the environment of the wash zone, such as changes in temperature and/or relative humidity. The power impressed on the heater device 628 can change for example from a first power level to a second power level, wherein the first power level is less than the second power level, as instructed by a reduction in the relative humidity of the air. The reduction in the power level is contemplated to occur by way of the configuration of the appliance in which vapor condenses on the thermal sink the thermal sink 116, 216, 300). That is, in one example, condensing of the vapor reduces the relative humidity of the air that is circulated throughout the appliance. The dryer air promotes evaporation of residual liquid that may reside on the objects in the appliance. Accordingly, in one example, the appliance can operate the heating element at a lower or reduced power level because evaporation is more likely to occur at lower air temperatures. In another example, changes in the temperature of the air in the appliance can induce changes in the power level impressed upon the heating device. Higher temperatures may, for example, facilitate reduced power levels for the heating device because the heating device need not be operated when the temperature of the air meets or exceeds some threshold temperature.

In another example, the controller 602 can regulate the speed of the fan 622 from a first speed to a second speed, wherein the first speed is less than the second speed when the heater is operating. This configuration will allow the temperature of the air in the tub to increase. The fan speed can increase from the first speed to the second speed such as when the heater is off to aid in the transport of water vapor to the area of condensation. In yet another example, the controller 602 is configured to regulate each of the fan 622 and the heater device 628 in response to humidity levels in the wash zone such as can be monitored using a humidity sensor (not shown). The combination of the speed of the fan 622 and the power level of the heater device 628 could be selected as the objects dry in the wash zone. Any one or combination of these concepts may, however, reduce power consumption of the appliance by way of re-circulating the air inside of the wash zone and corresponding regulation of the fan 622 and/or the heater device 628.

In view of the forgoing, appliances such as dishwashers are described and which are configured to re-circulate air in a manner that promotes drying of objects disposed therein. The elements of the proposed appliances operate to facilitate drying such as by directing the vapor-laden air in heat transfer relation to the thermal sink. This configuration reduces the relative humidity of the air, thereby permitting the heating element to be operated at a reduced power level during at least a portion of the drying cycle. In turn and as a result, the heating element will draw less power, and thus reduce the amount of energy consumed by appliance.

Where applicable it is contemplated that numerical values, as well as other values that are recited herein are modified by the term “about”, whether expressly stated or inherently derived by the discussion of the present disclosure. As used herein, the term “about” defines the numerical boundaries of the modified values so as to include, but not be limited to, tolerances and values up to, and including the numerical value so modified. That is, numerical values can include the actual value that is expressly stated, as well as other values that are, or can be, the decimal, fractional, or other multiple of the actual value indicated, and/or described in the disclosure.

This written description uses examples to disclose embodiments of the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims. 

1. A door assembly, comprising: a peripheral wall surrounding a door cavity, the peripheral wall having a first opening and a second opening exposing the door cavity to the environment; a thermal sink disposed in the door cavity; and an air moving device that is configured to draw air through the first opening and into the door cavity, wherein the thermal sink is configured with a surface on which condenses vapor in the air.
 2. A door assembly according to claim 1, further comprising a pathway disposed in the door cavity through which air flows from the first opening to the second opening, wherein the pathway exposes the air to the thermal sink.
 3. A door assembly according to claim 2, wherein the pathway comprises a duct coupled to each of the first opening and the second opening.
 4. A door assembly according to claim 3, wherein the duct is formed by a tube.
 5. A door assembly according to claim I, further comprising a conduit through which the condensed vapor flows out of the door cavity.
 6. A door assembly according to claim 1, wherein the thermal sink comprises a phase change material.
 7. A door assembly according to claim 6, wherein the phase change material is proximate the surface of the thermal sink.
 8. An appliance, comprising: a wash zone in which objects can be positioned to be washed; and a door assembly configured to seal the wash zone, the door assembly having a peripheral wall surrounding a door cavity in which is disposed a thermal sink with a surface on which condenses vapor in the air, wherein the door assembly is configured to draw air into the door cavity from an upper region of the wash zone and to expel the air from the door cavity into a lower region of the wash zone.
 9. An appliance according to claim 8, further comprising a sump zone proximate the lower region and in which a washing fluid is collected, wherein the door assembly is configured to flow the condensed vapor from the thermal sink into the sump zone.
 10. An appliance according to claim 8, wherein the door assembly comprises a duct in flow communication with the upper region and the lower region and through which flows the air.
 11. An appliance according to claim 10, wherein the duct comprises a conduit that extends from a first opening to a second opening in the peripheral wall.
 12. An appliance according to claim 10, wherein the duct is configured to expose the air to the thermal sink.
 13. An appliance according to claim 8, further comprising an air moving device proximate the upper region, wherein the air moving device is configured to move air from the upper region into an opening in the peripheral wall.
 14. An appliance according to claim 13, wherein the air moving device comprises a fan.
 15. A method of operating a dishwasher, said method comprising: activating an air moving device located proximate an upper region of the dishwasher, wherein the air moving device is configured to generate an outward flow of air from inside the dishwasher into a door cavity; regulating a heating element from a first power level to a second power level in response to a change in a characteristic of the environment of the dishwasher, wherein the air passes through the door cavity in thermal relation to a thermal sink.
 16. A method according to claim 15, wherein the air is ejected into a lower region of the dishwasher.
 17. A method according to claim 15, wherein the first power level is less than the second power level.
 18. A method according to claim 15, wherein the characteristic is temperature of air in the appliance.
 19. A method according to claim 15, wherein the characteristic is relative humidity of air in the appliance.
 20. A method according to claim 15, farther comprising regulating a speed of the air moving device in response to changes in one or more of the characteristic of the environment. 